The Copenhagen plank is a simple exercise for adductor strength and hip stability.
 
In a side plank position, place the top leg on a bench with the bottom leg under the bench. Lift the hips up until your body is in a straight line with the lower leg off the floor and hold.
 
Reduce the difficulty by keeping the foot of the lower leg on the floor to assist, and/or by moving the bench closer to the hips.
 
Purpose
The Copenhagen plank strengthens the adductors for strength balance and stability of the hip and to help protect against adductor strains.
 
Programming
Do 3-4 sets of 10-30 second holds.
 
Variations
The hip and knee can be partially flexed. Add dynamic work for the lower leg adductors by raising and lowering it as you hold the top steady.